Transmitter and receiver for digital broadcasting

Abstract

In order to alleviate stresses on a user, a transmitter comprises a channel coding section operable to encode input data stream according to a first modulation scheme, an additional information encode section operable to receive character data and additional information having a reserve area and including a transmission parameter relative to the first modulation scheme, to store the received character data in the reserve area of the additional information, and to encode the additional information in which the character data is stored according to a second modulation scheme with a smaller number of bits, which can be represented with a single symbol, than that of bits of a symbol to be used in the first modulation scheme; a multi-carrier modulation section operable to modulate multi-carriers with the data stream encoded according to the first modulation scheme and the additional information encoded according to the second modulation scheme.

1 . A transmitter comprising:
 a channel coding section operable to encode input data stream according to a first modulation scheme;   an additional information encode section operable to receive character data and additional information having a reserve area and including a transmission parameter relative to the first modulation scheme, to store the received character data in the reserve area of the additional information, and to encode the additional information in which the character data is stored according to a second modulation scheme using a smaller number of bits, which can be represented with a single symbol, than that of bits of a single symbol to be used in the first modulation scheme; and   a multi-carrier modulation section operable to modulate multi-carriers with the data stream encoded according to the first modulation scheme and the additional information encoded according to the second modulation scheme.   
     
     
         2 . A receiver comprising:
 an antenna section operable to receive transmission signals which is multi-carriers modulated with a data stream and additional information, the data stream being encoded according to a first modulation scheme, and the additional information being encoded according to a second modulation scheme using a smaller number of bits, which can be represented with a single symbol, than that of bits of a single symbol to be used in the first modulation scheme;   a character information decoding section operable to decode the character data stored in the additional information included in the transmission signals received by said antenna section; and   an image output section operable to output a character represented by the character data decoded in said character information decoding section.   
     
     
         3 . The receiver according to  claim 2 , wherein
 said character information decode section decodes the character data stored in the additional information if a receiving environment thereof is not good.   
     
     
         4 . The receiver according to  claim 3 , further comprising:
 a decode section operable to determine whether or not the receiving environment is good, to decode image data, audio data or character data multiplexed into the data stream if the receiving environment is good, and to provide an instruction to said character information decode section if the receiving environment is not good, wherein   said character information decode section decodes the character data included in the additional information in response to the instruction provided from said decode section.